.box {
  width: 750px;
  margin: 0 auto;
  background-color: #ddd;
  padding: 20px;
  border-radius: 5px;
  min-height: 100vh;
}
.box .btn-box {
  padding: 10px 0;
}
.box .btn-box button {
  border: none;
  outline: none;
  background-color: #409eff;
  color: #ffffff;
  padding: 8px;
  border-radius: 5px;
  cursor: pointer;
}
.box .btn-box button:hover {
  background-color: #1f8fff;
}
.box .students-table {
  border: 1px solid #ffffff;
  width: 100%;
  border-collapse: collapse;
  font-size: 12px;
}
.box .students-table tr {
  border: 1px solid #ffffff;
}
.box .students-table tr th {
  border: 1px solid #ffffff;
  padding: 6px;
}
.box .students-table tr td {
  border: 1px solid #ffffff;
  padding: 6px;
  text-align: center;
}
.box .students-table tr.t-header {
  background-color: #409eff;
  color: #ffffff;
}
.box .dialog {
  display: none;
  font-size: 12px;
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  z-index: 9999;
  background-color: rgba(0, 0, 0, 0.3);
}
.box .dialog .form {
  background-color: #fff;
  padding: 20px;
  border-radius: 5px;
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
}
.box .dialog .form .form-item {
  padding: 10px 0;
  display: flex;
  align-items: center;
}
.box .dialog .form .form-item label {
  padding: 0 10px;
  width: 50px;
}
.box .dialog .form .form-item input[type='text'] {
  border: none;
  border: 1px solid rgba(0, 0, 0, 0.5);
  outline: none;
  padding-left: 10px;
  height: 30px;
  width: 250px;
  border-radius: 5px;
}
.box .dialog .form .form-item span {
  padding: 0 10px;
}
.box .dialog .form .form-item.btns {
  justify-content: flex-end;
}
.box .dialog .form .form-item.btns div {
  background-color: #409eff;
  color: #ffffff;
  padding: 8px 20px;
  border-radius: 5px;
  margin-left: 10px;
  cursor: pointer;
  font-size: 12px;
}
.box .dialog .form .form-item.btns div:hover {
  background-color: #1f8fff;
}
